Sensor network system and data transfer method for sensing data

Abstract

To suppress a server processing load and a network load in a sensor network which accommodates a great number of mobile sensor nodes. Among a plurality of distributed data processing servers (DDS) for managing data of sensor nodes, a distributed data processing server (DDS) that is a home server to hold data of a mobile sensor node is set for each sensor node by a directory server (DRS). At each distributed data processing server (DDS), upon reception of the data from the sensor node, identification process is executed as to whether the data is sensor data to be managed by itself or another distributed data processing server. If a result of the identification is the sensor data to be managed by another distributed data processing server, the data is transferred to the distributed data processing server (DDS-1), which corresponds to the home server of the sensor data, based on setting of the directory server (DRS).

Description

CLAIM OF PRIORITY [0001] The present application claims priority from Japanese application P2005-85638 filed on Mar. 24, 2005, the content of which is hereby incorporated by reference into this application. BACKGROUND OF THE INVENTION [0002] This invention relates to a technique for use of information from many sensors connected to a network. [0003] Networks including the Internet have been recently used mainly for access to accumulated contents including documents, images, videos, or voices, the access being made through search engines, preset links, or the like. In other words, a technique for accessing stored contents has been established. [0004] To transmit real-time information, a streaming technology is known for continuously distributing images of a camera (WEB camera) installed in a predetermined position. Development has been recently made on a sensor network technology to obtain sensing data acquired from a great number of compact wireless sensor nodes through a network (e...

AI Technical Summary

Benefits of technology

[0006] When the sensors are mobile, a centralized server is employed to track positions of all the sensors and collects sensor outputs. Accordingly, a user can easily retrieve the positions when the sensor positions are changed (e.g., JP 2002-006937 A). However, when the number of sensors connected to this server is large, there could be bottlenecks in a server processing due to a heavy load or in a network due to traffic load for connecting the server with the sensors.

[0007] It is therefore an object of this invention to realize a sensor network which can easily obtain and retrieve real-time information from many sensors connected to a network, particularly to provide a data management system for mobile sensor nodes. It is a further object of this invention to suppress loads of a server and a network even when a great number of mobile sensors are used.

[0009] Thus, according to this invention, as the data can be transferred to the home server even when the mobile sensor node moves to another distributed server in the sensor network, it is possible to manage the sensing data in a unified manner. As the directory server does not need to directly manage the data and the position information of the mobile sensor node, it is possible to reduce a data processing load even when the number of mobile sensor nodes increases.

[0010] Each mobile sensor node does not need to hold information of the home server itself, and the management sever is required only to notify home server information of a relevant external sensor node for each arrival of a new external sensor node to the distributed server. Accordingly, even when a sensor network includes many mobile sensor nodes, a setting load on the mobile sensor node can be reduced, and excessive loads of the directory server and the network can be prevented. Thus, it is possible to manage a mobile sensor network in a scalable manner.

Problems solved by technology

However, there is a problem in that the search engine is not suitable for efficient retrieval of real-time information from a great amount of sensor information connected to the network, or to detection of change in information.

However, when the number of sensors connected to this server is large, there could be bottlenecks in a server processing due to a heavy load or in a network due to traffic load for connecting the server with the sensors.

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